Lighting fixture



Jan. 10, 1939. G. R, BAUMGARTNER A2,143,673

LIGHTING FIXTURE Filed May ll Inventor George R. Baumgartner, b V 5 fgHKZ( J tornegf Patented Jan. 10, 1939 UNITED sTATEs LIGHTING FIXTUREGeorge R. Baumgartner, Cleveland Heights, Ohio,

assignor to General Electric Company, a corporation of New YorkApplication May 11, 1937, Serial No. 141,958

4 Claims.

My invention relates to lighting fixtures and more particularly to alighting fixture adapted to be used for industrial lighting wherein thefixture is mounted near the ceiling and the light is directed downward.

An object of my invention is to provide a lighting fixture capable ofoperating efciently'with the more powerful light sources and ofeffectively distributing the light. The higher powered light sourcesrequires .special lighting fixtures since the greater amount of lightincreases the brightness of the fixture and produces glare. Accordingly,lighting fixtures priorvto my invention were made of considerable depthin order to shield the brighter portions of the light source and fixturefrom observers located to one side thereof and in position to see thevrefiector in the normal angles of vision. To reduce the glare from thefixture itself the reflecting surfaces thereof were made diffuse incharacter which caused the light to be repeatedly reflected within thefixture and reduced the efiiciency thereof and the control over thedirection of reflection therefrom.

According to my invention, the lighting fixture comprises threeref-lector sections, one of which is a specular or semi-specularrefiecting surface located above the light source for directing downwardand sideward at a relatively small angle from the vertical a largeportion of the light projected upward from`the light source. A secondreflector section consists of a diffuse reflecting surface extendingoutward and downward from the edge of the first-mentioned reflectorsection 'for directing the remainder of the light emitted by the lightsource above horizontal to the area directly below the lighting fixture.A third section consists of a reflecting surface mounted below the lightsource for intercepting and redirecting the light projected downwardfrom the light source back upward to the other reflector sections. Theuse of the specular or semi-specular reflector section permits makingthe lighting fixture shallow since it appears to be unlighted exceptwhen viewed from vthe area being illuminated by it. Because of theshallowness of., the lighting fixture and the direct reflectingcharacteristic of the specular or semi-specular reflector section, themajority of the light passes` from the xture after being reflected bythe upper portion thereof but once. This feature is largely responsiblefor the high efficiency Vof the lighting fixture. The distribution' oflight from the specular or semi-specular reflector is such that it neverfalls within the normal angles of i' vision and -is not glare-producing.',Ihere is no (Cl.l 240-78) possibility of -glare from other portions ofmy fixture because no light can pass downward from the light source dueto the reflector mountedL consisting of a downwardly extending rim ispreferably added to the diffuse reector section to prevent glaretherefrom. Other features and advantages of myinvention will be apparentfrom the description which follows of a species thereof and from theaccompanying drawing.

In the drawing, Fig. 1 is a vertical section through a lighting fixturecomprising my invention, and Fig. 2 is a graphical representation of the-percentage and direction of reflections from different materials fromwhich my lighting fixture may be made.

The lighting fixture shown in Fig. 1 is comprised of three reflectorsections I0, II and I2, the first ofv which is located directly aboveAthe incandescent lamp I3, the second of which ex- -tends outward anddownward from the edge of the first section, and the third of which ispreferably in the form of a reflecting coating on the bowl of the lampbulb below the center of the filament indicated at Il. In thisparticular case `the first two reflector sections I Il and II areattached directlyto each other and form a unit which is mounted on thehusk I5 surrounding the socket I6 for the lamp I3. Both the husk I5 andthe socket I6 are mounted on the usual downwardly extending conduit orpipe I1.

The first reiiector section I0 which contributes greatly to the highefficiency of the fixture is either specular or has a slightlydepolished senilspecular surface and directs substantially all of thelight intercepted by it downward in the defi.- -nite directionsindicated by the lines 22. Y A de polished surface is preferred, sincetheV reflection perceived by an observer looking upward into thelsurface is not so bright or pronounced. To estab- A lishthe character ofmaterial suitable for the lust inside the rim particularlyspecular'vltreous enamel produced by the Ferro Enamel Company ofCleveland, Ohio, gave the reflection shown by the dot-dash line I9.

'I'he depolished surface referred to above was produced by etching thealuminum alloy Alzak" lightly with an lacid and it reflected light asshown by the dotted line 20. Obviously degrees of depolishing andvarious other materials having similar light reflecting properties maybe used for the reflecting surface, and I wish to include within thescope of my invention any material for the reflector section |0 whichreflects directly at least thirty per cent of the light intercepted byit. 'I'he shape of the said reflector section I0 is such as to redirectthe radiation from the filament I4 downward and sideward 2| andilluminate an area thereabout. To illustrate the direction of theradiation the lines 22 are drawn from the midpoint 23 of the filamentI4. In designing the curvature of this reflector section IIJ, a point 24was taken above the.actual location of the filament (actually about oneand one-fourth inches thereabove) and the curvature was made such thatthe light directed from this point 24 and redirected by said section I0cleared the rim 2| of the fixture as shown by the dotted lines 25. Thispoint 24 was taken at a position intended to duplicate the most extremecondition possible to make sure that the light from all parts of thefilament I4 and a substantial part of the light passing through afrosted neck portion of the lamp I3 strikes the reflector section I 0 atsuch an angle as to cause it to pass directly out of the fixturetherefrom.

'Ihe reflector section II is preferably of a diffusingcharacter such asthat produced by white vitreous enamel or by a more deeply etchedsurface of the aluminum alloy Alzak. The reflection characteristics ofthese materials are shown by the lines 26 and 2'I respectively in thegraph shown in Fig. 2. The said reflector section |I is shaped so thatwhatever direct reflection is given off by it is directed downward belowthe xture, as shown by the rays 22', and cannot produce glare except toan observer located directly below the xture and looking upward into it.For normal service this rsurface is preferably made of enamel or someother material giving very little direct radiation, but if the fixtureis mounted some distance above the area to be illuminated a less diffusematerial, such as the more deeply etched Alzak, is preferred. A materialgiving less than twenty-five per cent direct reflection is preferredfor'this reflecting surface Il.

The reflector I2 may be either a silvered or other reflecting coating onthe lamp bulb, as shown, or it may be a cap attached thereto and ineither case functions both to prevent light from passing directlydownward from the lamp and producing glare and to redirect light upwardinto the fixture to prevent loss thereof. I prefer to make the saidreflector I2 spherical in shape so that the light redirected therebystrikes the fixture at substantially the same angle as the light fromthe filament I4.

If the fixture comprises'simply the reflecting surfaces I0, II and I2,there is still possibility of glare from the upper portion 28 of thelamp bulb if it is frosted. To prevent this from occurring, thedownwardly extending rim 2| is preferably attached to the reflectingsurface Ato shield said bulb neck from the' view cf an observer notdirectly below said xture. 'I'his rim various,

2| is preferably coated with a white vitreous enamel or presents someother diffusing surface since it receives some light, particularly fromthe reflecting surface What I claim as new and desire to secure byLetters Patent of the United States is:

1. A lighting fixture comprising means for supporting an electric lamp,a comparatively shallow reflector surrounding said lamp and having asubstantially horizontal slightly concave section located above saidlamp with a surface which reflects directly at least about thirty percent of the light intercepted by it, said section being shaped to directlight from said lamp downward and sideward directly out of the fixture,said reflector comprising a second section having a surface whichdiffuses at least about seventy-five per cent of the light interceptedby it, said second section being concave -and extending downward fromthe edge of said first-mentioned section around said lamp so as toconcentrate and'direct the light reflected thereby directly below thefixture, said second section being so arranged as to be out of the pathof light reflected from said first-mentioned section, and anotherreflector located below said lamp for directing the downwardly projectedlight from said lamp backtoward said first-mentioned reflector.

2. A lightingxture comprising means for supporting an electric lamp, acomparatively shallow reflector surrounding said lamp and having asubstantially horizontal slightly concave section located` above saidlamp with a semi-specular reflecting surface, said section being shapedto direct light from said lamp downward and sideward directly out of thefixture, said reflector comprising a second section having alight-diffusing surface, said second section being concave and extendingdownward from the edge of said first-mentioned section around said lampso as to concentrate and direct the light reflected thereby directlybelow the fixture, said second section being so arranged as to be out ofthe path of light reflected from said first-mentioned section, andanother reflector located below said reflector surrounding said lamp andhaving a r substantially horizontal slightly concave section locatedabove said lamp with a semi-specular reflecting surface, said sectionbeing shaped to direct light from said lamp' downward and sidewarddirectly out of the fixture, said reflector comprising a second sectionhaving ai light-diffusing surface, said second section being concave andextending downward from the edge of said first-mentioned section aroundsaid lamp so as to concentrate and direct the light reflected therebydirectly below the fixture, said second section being sof arranged as tobe out of the path of light reflected from said first-mentioned section,and a substantially semi-spherical reflector located below said lampwith its center of curvature substantially at the centerof the lightsource in said lamp for directing the downwardly projected light fromsaid lamp back toward said first-mentioned reflector.

-4. A lighting fixture comprising means for supporting an electric lamp,a comparatively shallow reflector surrounding said lamp and having asubstantially horizontal slightly concave section located above saidlamp back toward said first-- with a semi-specular refiecting surface,said section being shaped to direct light from said lamp downward andsideward directly out of the fixture, said reector comprising a secondsection having a light-diffusing surface, said second section beingconcave and extending downward from the edge of said first-mentionedsection around said lamp substantially to the level of the light sourcetherein so as to concentrate and direct the lightreected therebydirectly below the fixture, said second section being so arranged as tobe out of the path of light reected from said mst-mentioned section, asubstantially cylindrical rim portion extending downward from theperiphery of said second reflector section but terminating at its loweredge short of the path of the light reflected lfrom said first-mentionedsection, and another GEORGE R. BAUMGARTNER.

